Treatment of black powder



Patented July 15, 1930 UNITED STATES PATENT OFFICE HENRY E. ELLSWORTI-I, OF SIMSBURY, CONNECTICUT, ASSIGNOR TO THE ENSIGN-IBICK- FORD (30., OF SIMSBURY, CONNECTICUT, A CORPORATION OF CONNECTICUT TREATMENT OF BLACK POWDER No Drawing.

as to effectually control its burning speed;

(2) the treatment of explosive, and particu larly black powder, so as to make it less hygroscopic and therefore more .desirable for use in safety fuse; (3) the treatment of explosive so as to retard its combustion without affecting its dependability; and (4) to provide a slow burning powder adaptable for use in safety fuse which will enable the user to economize on length.

In the manufacture of powder, and particularly black, saltpeter powder, for use in safety fuse, the most dependable burning speeds are obtainable from what are known as well-balanced powders. An example of such powder has the following composition 75% saltpeter, 13% charcoal and 12% sulphur. In practice it is customary to vary these proportions, and especially the charcoal and sulphur content, in order to produce changes in burning speed. In this connection, efforts have been made from time to time to slow down powder by mixing with it inert materials such as clay, brick dust, rosin, etc. The difliculty encountered in this method appears to be chiefly due to the fact that when a small amount is added, the powder grains lie contiguous to each other, and though there are not as many grains in a given area, the rate of propagation of the flame is but little retarded, but if a sufficient quantity of inert material is added to produce a marked effect in the burning speed, the powder grains are sometimes separated from each other by grains of inert material and at once irregularities in speed occur. Indeed, it often happens that the grains are sufliciently cut off from one another to arrest the combustion. Other methods, such as altering the composition of the powder, have also been resorted to 0 for retarding the combustion of the powder Application filed November 16, 1927. Serial No. 233,740.

of cellulose compounds of proper dilution or viscosity, and then drying the treated powder, there remains admixed with, deposited or coated upon the grains of powder or penetrated into the minute interstices of the grains a film or residue of suitable combustible cellulose compound which acts as a retardent to the combustion of the powder, but since said cellulose compound is itself inflammable it does not completely check the progress of the burning powder.

The method of treatment may be carried out in any preferred manner, and broadly stated, consists in moistening or dampening the granular powder with a solution of proper dilution of nitrocellulose dissolved in a volatile solvent and evaporating away the solvent which probably leaves the powder with a film of nitrocellulose of desired thickness enclosing the grains or admixed therewith and then mixing the dried powder thoroughly. I have found that a solution of nitrocellulose, of reduced viscosity provides a coating to the powder grains which is hard and tough. An example of such nitrocellulose solution is known in the trade as Duco Dip No. 1501. By varying the dilution or the visocity of the nitrocellulose solution, it will be apparent that upon evaporation of the volatile solvent the thickness of the enclosing film about the powder grains will be different, and use is made of this knowledge to effectively control the speed of combustion of the powder by varying the thickness of such film of nitrocellulose.

While I have described the principles of my invention and the broad manner of practicing the same, I do not wish to be limited to any specific nitrocellulose solution or other cellulose solutions for treating explosives in granular form, but deem it within the scope of my invention to employ any substance which, after being used to moisten the grains of explosive will leave admixed with or deposited thereon a residue film or coating of suitable combustible substance.

5 WVhat I claim is:

1. The treatment of black powder that comprises moistening the powder with a solution of nitrocellulose dissolved in a volatile solvent and evaporating away the solvent.

2. The treatment of black powder that comprises moistening the powder with a solution of nitrocellulose dissolved in a volatile solvent, which solution will not break down the composition of the powder to any appreciable extent, and evaporating away the solvent.

3. The treatment of black powder that comprises moistening the power with a solution of nitrocellulose of reduced viscosity and evaporating away the solvent.

4. The method of retarding the speed of combustion of black powder, that comprises coating the powder grains with a film of nitrocellulose.

5. The method of rendering black powder less hygroscopic that comprises coating the powder grains with a film of nitrocellulose without breaking down to any appreciable extent the composition of the powder.

6. The method of effectively controlling the speed of combustion of black powder, that comprises moistening the powder with a solution of proper dilution of nitrocellulose dissolved in a volatile solvent, and evaporating away the solvent to leave a film of nitrocellulose of desired thickness enclosing said grains.

7. Black powder, the grains of which are coated with a film of hard, tough nitrocellulose.

8. As a new explosive product for use in safety fuses and the like, black powder, which has been moistened with a solution of nitrocellulose dissolved in a volatile solvent and then dried.

4 9. As a new explosive product for use in safety fuses and the like, black powder, the grains of which are coated with a film of nitrocellulose.

In witness whereof, I have hereunto signed my name.

HENRY E. ELLSWORTH. 

